There are tons of garbage heart rate sensor–enabled “fitness trackers” and sport watches out there. Most of them are about as effective at tracking your heart rate as your phone alarm is at getting you out of bed. In that sense, the Suunto Spartan Sport Wrist HR is to tracking as a bucket of ice water over your face is to waking up. It’s an incredibly effective heart rate–sensing watch and the best running watch that Suunto has ever built. Using it was the single best thing I’ve done for my running routine since switching to a zero-drop shoe.

A bit of background: I’m not, nor have I ever been, one to run with any sort of technology on me. I don’t run with headphones, or my phone, or a watch, or any type of sensor (usually). I feel like it weighs me down, and I’m less able to tune out and focus on my run when there are all sorts of electronics to fiddle with and worry about. I prefer the beat of my feet hitting the pavement to that of the kick drum. And yet, because it wears very small and comfortably for its size, I had no trouble at all transitioning to wearing the Suunto. It’s not exactly the type of thing that you’d wear out to the bar, but it isn’t as tactical-looking and outdoor-oriented as the Spartan Ultra or Traverse series.

By the Numbers

Water Resistance: 100m
Trackable Sports: 80
Sensors: GPS/GLONASS, Valencell Optical Heart Rate
Price: $499

That easy integration applies to the software as well. You get to the menus using either the color touch screen or the three buttons on the right side of the watch face. The touchscreen is responsive, but not so much so that you’ll keep inadvertently changing the menu. You have access to an adjustable watch face, a step counter, exercise mode, navigation, a logbook that stores your workouts internally and a stopwatch. Exercise mode allows you to track over 80 different sports, including running, circuit training and cycling. Navigation mode lets you follow a pre-loaded route. The watch utilizes both GPS and GLONASS for supremely accurate route and distance tracking. It will connect to your phone to display texts or your calendar entries through the Movescount app — but I kept the notifications turned off so that I could focus solely on my run and cadence instead of what I was doing afterward.

In run mode, which is what I used most, the watch will vibrate and audibly alert you to each mile you tick off. It’s a nice reminder to look down and check your heart rate — which will be the most accurate reading you’ve ever seen from a running watch. Instead of tossing in a second-rate optical sensor, Suunto awaited the completion of Valencell’s most advanced, industry-leading biometric sensor, the PerfomTek. During run mode, the menu displays distance traveled, pace, overall run time, heart rate, location, elevation and lap times. When you’ve finished your workout, there’s an option to rate your workout from excellent to poor; the watch stores your ratings and run data and uses them to adjust recovery times and a few other statistics.

Perhaps the most impressive feature of the Spartan Sport Wrist HR is its battery life.

Perhaps the most impressive feature of the Spartan Sport Wrist HR is its battery life. Suunto claims a battery life of 12 hours during training mode, but with normal use, I saw days go by without having to recharge — right around three, to be exact. It’s worth noting that I didn’t have it tracking my heart rate continuously; I only did so when I was running. Having 24/7 heart rate tracking activated would significantly affect the battery life. Nothing is worse than grabbing your running watch to put some miles in only to realize that you forgot to charge it the night before. For a color touch screen device running GP/GLONASS and a heart rate sensor, 12 active hours is nothing short of incredible.

If you’re serious about your fitness and need the most accurate data in the smallest, most approachable package possible, this is your fitness tracker. If you’re looking to see how many steps you can log in a day, there are other products on the market that accomplish that for a significantly smaller sum. But in the realm of performance running watches, our friends in Finland nailed this one. I’ll continue running with it until someone else tops it.